@Bob_HoodI think the article refers to the fact that the clients i.e. the customers are the ones who make most of the configuration mistakes, and get themselves into hot water. It also relates to many customers not fully understanding the Shared Responsibility Model (SRM) which the Cloud Providers impose on their clients too.
But in general the customer or clients are the ones who generally make the most mistakes or configuration issues. I too believe human beings are required, but I do believe human beings with sufficient knowledge add value i.e. auditors, and cyber security professionals or check lists such as those provided by CIS for instance.
The article is a little too generic and not specific, as though it is attempting to put a blanket statement on human clients or customers.